Design of a heat-recirculating combustor for a thermophotovoltaic system

T.Y. Kim, H.K. Kim, O.C. Kwon
School of Mechanical Engineering Sungkyunkwan University,
Korea

Keywords: thermophotovoltaic (TPV)

Summary:

Recently, the demand for light, fast-charging and long-lasting portable power sources to replace current lithium-ion batteries has been increased because of development of portable electronic devices such as laptop computers, cellular phones and signal equipments. Power systems using combustion of hydrocarbon fuel are considered one of the alternatives since the specific energy of hydrocarbon fuel, e.g., butane (12,700 Wh/kg), is much larger than that of lithium-ion batteries (100−265 Wh/kg) and the fast-charging is possible when hydrocarbon fuel is used. In the present study, a new combustor configuration for a thermophotovoltaic (TPV) system in which thermal energy is directly converted into electrical energy through thermal radiation is investigated experimentally. The combustor as a thermal heat source is designed for a 10–30 W power-generating TPV system. The combustor consists of an emitter (combustion chamber), injection nozzles, a recuperator and a quartz shield. To satisfy the primary requirements for designing the combustor (i.e., stable burning in the combustor chamber, maximized heat transfer through the emitting walls, but uniform distribution of temperature along the walls), the multiple injection configuration with annular-type nozzles and the cylindrical emitter with the quartz shield to apply a heat-recirculation concept are adopted to the present combustor. Results show that the heat recirculation substantially improves the performance of the combustor. Compared with conventional combustors with no heat-recirculation, the efficiency of the combustor has been enhanced and the observed thermal radiation from the emitter walls indicates that heat generated in the emitter is uniformly emitted. Thus, the present combustor configuration can be applied to the practical TPV systems without any moving parts (i.e., without frictional losses and clearance problems). The surface area to volume ratio of the combustion chamber and an array of injection nozzles substantially affect thermal characteristics.